Anneliese Mackintosh’s short story collection Any Other Mouth was published in 2014.
Photograph: Colin McPherson/Alamy

Ottila McGregor has a new year resolution. She’s going to make herself happy – “so happy it hurts,” she tells her therapist, “SO FUCKING HAPPY IT REALLY FUCKING KILLS,” she writes to herself. At the moment, she’s just hurting herself, via a destructive relationship (an affair with her boss) and too much drink. That’s not too much drink in a Bridget Jones, fake-horrified, unit-totting sort of way. It’s too much drink in a sexting-your-manager-again, tweeting-that-you-want-to-die, having-your-stomach-pumped way. So Ottila is going to “turn everything around”, confiding the process to the “grief scrapbook” she’s assembling inside a vandalised copy of The Little Book of Happy. Ottila knows about grief scrapbooks: she works in a support centre for people with cancer and their families. What is she grieving for? Booze, of course – and other things, the things her drinking tried to chase away.

The Little Book of Happy doesn’t actually exist, but I assumed it was real until I checked: one of those small, square hardbacks where inspiring quotations nestle against platitudinous advice. So Happy It Hurts, on the other hand, is a pleasingly unfamiliar kind of book. Anneliese Mackintosh’s debut novel (a follow-up to the scabrous short-story sequence Any Other Mouth, many of the themes of which are revisited here) is told through Ottila’s diary entries, transcripts of therapy sessions, emails, Snapchats and receipts. It’s an epistolary novel for a hyperconnected world, and the effect is appropriately chaotic – the reader feels at first a little like a drunk turning out her pockets and trying to reconstruct another night of blackout from the detritus she’s accumulated.

Ottila belongs to the great sisterhood of the Female Fuck-Up. Not the eroticised trainwrecks male writers love to invent, but the real-deal ones like Phoebe Waller-Bridge’s Fleabag, the ones whose wisecracks come with the authentic acid burn of a wretched hangover and human faults. Ottila is selfish, and she knows it. The bad sex she has is not a pornographic excess of humiliation filtered through the male gaze for the reader’s grubby enjoyment but, seen from her perspective, clammy and unsatisfying and barely remembered. She has bad judgment, which means that when she decides to distract herself from drinking by developing a new crush, you worry for her.

This crush, on a vulnerable man-bear called Thales who works in the canteen, forms the backbone of the plot, their burgeoning relationship waylaid by Austenish imbroglios of manners (although Ottila’s faux pas involve more binge drinking and bad sex than the average Austen heroine). But, also Austenishly, the love story is something of a McGuffin. As much as you’re rooting for Ottila to get her man, that’s not the point; the point is whether she can gain the moral wisdom to live a better kind of life. She’s an Emma steeped in ethanol.

Ottila’s fragile sobriety demands that she finally attend to the things she’s spent years obliterating. That means addressing her grief at her father’s death, and her guilt at her relationship with her sister Mina, who has Asperger’s syndrome, obsessive-compulsive disorder, anxiety and a tendency to self-harm. “There’s an alternate reality out there somewhere, in which I didn’t bully her growing up … But then what are big sisters for?” writes Ottila, full of bitter self-reproach at three months dry. Mina is given electroconvulsive therapy, which wrecks her short-term memory, leading to a plaintive Snapchat where Mina asks Ottila to move to a more permanent form of messaging: the way Snapchats ping out of existence makes poor Mina feel even more unstable. The media Mackintosh chooses for her story are always smartly entwined with character and plot.

At one point, Ottila’s scrapbook includes a funding application to Manchester Museum for a project called “Our Love Began With a Coin Touched by Alexander the Great”, commemorating the first time Thales said “I love you”. In it, items of significance to the nascent couple would be scattered through the museum so visitors could vicariously share their feelings: an empty takeaway cup from their first coffee together, a sandwich box used to sneak a note through the hospital. It is, of course, rejected; but the idea that life must be curated, with both good and bad exhibited and reinterpreted, is at the centre of this raw, funny and untidily generous novel.

•So Happy It Hurts is published by Jonathan Cape. To order a copy for £12.74 (RRP £14.99) go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.